1. Field
The present invention relates to a numerical analysis method represented by a structural strength evaluation and, more particularly, to a structural analysis apparatus, a structural analysis method, and a structural analysis program that evaluates the strength of a structure in a development process of, e.g., a portable electronic device.
2. Description of the Related Art
In structural simulation which is taken as an example of structural analysis, an accurate result cannot be obtained in the case where a maximum stress occurring when a load is applied to a structure is calculated, unless the mesh of a stress concentration zone is sufficiently dense. On the other hand, in the case where a part to be actually evaluated in a to-be-modeled area is very small due to a limitation of a restraint condition or loading condition, if the entire evaluation part is divided into meshes of very small size for sufficient evaluation, a calculation amount becomes large. In light of this, a calculation is performed, in two stages, for an entire model. The first stage is performed on a relatively rough model, while the second stage is performed on a detailed model obtained by partially modeling (zooming) the part being evaluated.
Therefore, when numerical analysis of a detailed partial structure (detailed model) is performed for an entire structure (entire model) in a conventional structural analysis, extraction of the detailed model, that is, which part of the entire model is zoomed is manually performed by operators according to their individual judgment.
As a technique related to the prior art, there is known a technique in which analysis is performed by using the entire model of a structure to be analyzed. A partial model is obtained by extracting a part of the entire model of the structure. The detailed partial model is used for analysis of the extracted part and a difference between the analysis results of the partial model and detailed partial model is calculated (refer to, e.g., Patent Document 1: Jpn. Pat. Appln. Publication No. 11-149466).
Further, there is known a technique that allows a mesh with less distortion to be created for a regional model cut out from the entire model easily and immediately (refer to, e.g., Patent Document 2: Jpn. Pat. Appln. Publication No. 7-55656).
When the detailed model is calculated for the abovementioned extraction process, a boundary value of the detailed model which has been calculated for the entire model is used as a boundary condition. At this time, modeling needs to be performed such that the boundary value is not changed due to a difference in the shape between the detailed model and entire model. However, the boundary of the detailed model must be set in advance. Therefore, in the case where an operator arbitrarily sets the boundary of the detailed model as in the conventional way, there is a high possibility that the boundary value is changed due to a difference in the shape between the detailed model and entire model. Further, it is difficult to determine whether the result obtained in the detailed model is sufficiently accurate or not, so that recalculation must be made using the detailed mesh model for verification.